Spectroscopic imaging combines digital imaging and molecular spectroscopy techniques, which can include Raman scattering, fluorescence, photoluminescence, ultraviolet, visible and infrared absorption spectroscopies. When applied to the chemical analysis of materials, spectroscopic imaging is commonly referred to as chemical imaging. Instruments for performing spectroscopic (i.e., chemical) imaging typically comprise image gathering optics, focal plane array imaging detectors and imaging spectrometers.
In general, the sample size determines the choice of image gathering optic. For example, a microscope is typically employed for the analysis of sub micron to millimeter spatial dimension samples. For larger objects, in the range of millimeter to meter dimensions, macro lens optics are appropriate. For samples located within relatively inaccessible environments, flexible fiberscopes or rigid borescopes can be employed. For very large scale objects, such as planetary objects, telescopes are appropriate image gathering optics.
Often the array under study includes multiple samples arranged on an array card. Conventional arrays include 4 in×6 in well plates having typically 96 wells for receiving samples. The samples in each well can include similar or dissimilar substances. Thus, for example, a conventional array can include as many as 96 different samples. To obtain a spectral image or spectra(um) for each sample with a conventional micro-Raman instrument an excitation in the form of a spot laser beam of desired wavelength (λillium) is directed to one of the 96 samples. After a suitable image or spectra(um) of the first sample is procured, the illumination source is directed to the subsequent well and the process is repeated. The conventional method of serially imaging each sample is time-consuming and labor intensive.